The answer
Can the unit go anywhere on an outside wall?
An indoor unit needs a position that distributes air through the room without blowing directly on people, allows filter access and has a workable pipe and condensate route. An outside wall can help routing, but it is not automatically the best location.
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Start with occupants and airflow
A unit over a desk, bed or sofa may create uncomfortable draughts even if capacity is correct. Furniture, partitions and ceiling shape affect how supply and return air move. The installer should explain where the air will travel and how the room's thermostat senses temperature.
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Check the hidden work
Condensate must drain reliably; a gravity route may be preferable where practical, while a pump adds noise and a maintenance item. Pipework and cables need a route to the outdoor unit. Leave access to clean filters and service the unit, and consider what a future redecorating or furniture change will do to it.
Where this guidance comes from
Check the original guidance.
These primary sources support the technical or scheme points above. Rules can change; follow the current source before making a commitment.
Apply this to your property
Find a position that feels right in the room.
A free survey can look at how the room is used, then test unit position, airflow and drainage together.